Rush Limbaugh seems to think he knows why Robin Williams died in an apparent suicide earlier this week -- and it's because unhappiness is an attitude of the political left.

The leftist attitude is "one of pessimism and darkness, sadness -- they're never happy, are they?" Limbaugh said on Tuesday's broadcast of his radio show. "They're always angry about something. No matter what they get, they're always angry."

While there don't seem to be many studies on political leanings and suicide rates, research published last year found that suicide rates tend to be higher in states that vote Republican and have a higher rate of gun ownership.

A book by James Gilligan, Why Some Politicians Are More Dangerous Than Others, says that suicide and violence rates rise during Republican presidencies and fall during Democratic administrations.

And another study found higher suicide rates in Australia and the United Kingdom when conservative governments are in power.

Rush's comments were extremely rude. I can't believe people still listen to this guy.